A sorely needed cellphone feature

A lecture attendee reacted to my data about the scary extent of disruption caused by endlessly ringing cellphones by saying: “I keep my cellphone turned on only in case my child calls – I wish it would only ring for him!”

Now, here is a feature that is painfully needed, and obviously useful: Allow the user to specify which callers the phone will ring for, and which it will not, when you put it into a “Silent” mode. Or use “vibrate” as part of the equation: Ring for calls from an emergency-prone dependent, vibrate for close family and coworkers, let all others leave a message.